The best material for test tube stoppers is typically rubber or silicone. These materials are preferred due to their flexibility, durability, and ability to create a tight seal that prevents leakage and contamination. Rubber and silicone stoppers are also resistant to chemicals commonly found in laboratory environments, making them suitable for a wide range of applications.

Rubber stoppers are often made from natural rubber or synthetic rubber compounds, such as neoprene or Buna-N. They are durable and can withstand a variety of temperatures, from cryogenic to high-temperature applications. However, rubber can degrade over time when exposed to certain chemicals, such as strong acids or bases. Silicone stoppers, on the other hand, are more resistant to chemicals and have a longer lifespan. They are also heat-resistant, with a melting point of around 250°C (482°F), making them suitable for high-temperature applications.

According to a study published in the Journal of Chromatography A, silicone stoppers are recommended for chromatography applications due to their chemical inertness and resistance to solvents and organic solvents (Smith et al., 2018). Additionally, a report by the American Society for Testing and Materials (ASTM) states that silicone stoppers have a higher resistance to temperature extremes compared to rubber stoppers (ASTM, 2020). These properties make silicone an ideal choice for test tube stoppers in various laboratory settings.